[v2,0/3] tools/nolibc: add testcases for vfprintf

  vfprintf() is complex and so far did not have proper tests.

This series is based on the "dev" branch of the RCU tree.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
Changes in v2:
- Include <sys/mman.h> for tests.
- Implement FILE* in terms of integer pointers.
- Provide fdopen() and fileno().
- Link to v1: https://lore.kernel.org/lkml/20230328-nolibc-printf-test-v1-0-d7290ec893dd@weissschuh.net/

---
Thomas Weißschuh (3):
      tools/nolibc: add wrapper for memfd_create
      tools/nolibc: implement fd-based FILE streams
      tools/nolibc: add testcases for vfprintf

 tools/include/nolibc/stdio.h                 | 60 +++++++++++----------
 tools/include/nolibc/sys.h                   | 23 ++++++++
 tools/testing/selftests/nolibc/nolibc-test.c | 78 ++++++++++++++++++++++++++++
 3 files changed, 134 insertions(+), 27 deletions(-)
---
base-commit: a63baab5f60110f3631c98b55d59066f1c68c4f7
change-id: 20230328-nolibc-printf-test-052d5abc2118

Best regards,
  

Thomas,

On Sun, Apr 02, 2023 at 01:02:44PM +0000, Thomas Weißschuh wrote:
> vfprintf() is complex and so far did not have proper tests.
> 
> This series is based on the "dev" branch of the RCU tree.

I've just ran it with glibc to see:

  $ gcc nolibc-test.c  
  $ ./a.out vfprintf
  Running test 'vfprintf'
  0 empty "" = ""                                                  [OK]
  1 simple written(3) != read(0)                                  [FAIL]
  2 string written(3) != read(0)                                  [FAIL]
  3 number written(4) != read(0)                                  [FAIL]
  4 negnumber written(5) != read(0)                               [FAIL]
  5 unsigned written(5) != read(0)                                [FAIL]
  6 char written(1) != read(0)                                    [FAIL]
  7 hex written(1) != read(0)                                     [FAIL]
  8 pointer written(5) != 3                                       [FAIL]
  Errors during this test: 8

The main issue was that glibc uses buffered writes by default.

I could fix them with fflush() (which we don't have so it required an
ifndef), and this also made me realize that we were missing an fclose()
as well for compatibility with glibc. With this it got better:

  Running test 'vfprintf'
  0 empty "" = ""                                                  [OK]
  1 simple "foo" = "foo"                                           [OK]
  2 string "foo" = "foo"                                           [OK]
  3 number "1234" = "1234"                                         [OK]
  4 negnumber "-1234" = "-1234"                                    [OK]
  5 unsigned "12345" = "12345"                                     [OK]
  6 char "c" = "c"                                                 [OK]
  7 hex "f" = "f"                                                  [OK]
  8 pointer written(5) != 3                                       [FAIL]
  Errors during this test: 1

This is caused by glibc emitting "(nil)" while we emit "0x0" for a NULL
pointer since we use the same code as when dumping integers. I could fix
that one as well by printing (void*)1 instead, which shows "0x1" for both.

This gives me the patch below on top of yours, which I think would make
sense to integrate in this form or a simplified one if we manage to add
fflush() and fclose() earlier.

What do you think ?

Thanks,
Willy


diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 28a8d77078dc..2958dc3eca93 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -678,6 +678,7 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char
 	int ret, fd, w, r;
 	char buf[100];
 	va_list args;
+	FILE *memfile;
 
 	fd = memfd_create("vfprintf", 0);
 	if (fd == -1) {
@@ -685,8 +686,14 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char
 		return 1;
 	}
 
+	memfile = fdopen(fd, "w+");
+	if (!memfile) {
+		pad_spc(llen, 64, "[FAIL]\n");
+		return 1;
+	}
+
 	va_start(args, fmt);
-	w = vfprintf(fdopen(fd, "w+"), fmt, args);
+	w = vfprintf(memfile, fmt, args);
 	va_end(args);
 
 	if (w != c) {
@@ -695,12 +702,19 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char
 		return 1;
 	}
 
+#ifndef _NOLIBC_STDIO_H
+	fflush(memfile);
+#endif
 	lseek(fd, 0, SEEK_SET);
 
 	r = read(fd, buf, sizeof(buf) - 1);
 	buf[r] = '\0';
 
+#ifndef _NOLIBC_STDIO_H
+	fclose(memfile);
+#else
 	close(fd);
+#endif
 
 	if (r != w) {
 		llen += printf(" written(%d) != read(%d)", w, r);
@@ -737,7 +751,7 @@ static int run_vfprintf(int min, int max)
 		CASE_TEST(unsigned);     EXPECT_VFPRINTF(5, "12345", "%u", 12345); break;
 		CASE_TEST(char);         EXPECT_VFPRINTF(1, "c", "%c", 'c'); break;
 		CASE_TEST(hex);          EXPECT_VFPRINTF(1, "f", "%x", 0xf); break;
-		CASE_TEST(pointer);      EXPECT_VFPRINTF(3, "0x0", "%p", NULL); break;
+		CASE_TEST(pointer);      EXPECT_VFPRINTF(3, "0x1", "%p", (void*)0x1); break;
 		case __LINE__:
 			return ret; /* must be last */
 		/* note: do not set any defaults so as to permit holes above */
  

On 2023-04-02 18:43:21+0200, Willy Tarreau wrote:
> Thomas,
> 
> On Sun, Apr 02, 2023 at 01:02:44PM +0000, Thomas Weißschuh wrote:
> > vfprintf() is complex and so far did not have proper tests.
> > 
> > This series is based on the "dev" branch of the RCU tree.
> 
> I've just ran it with glibc to see:
> 
>   $ gcc nolibc-test.c  
>   $ ./a.out vfprintf
>   Running test 'vfprintf'
>   0 empty "" = ""                                                  [OK]
>   1 simple written(3) != read(0)                                  [FAIL]
>   2 string written(3) != read(0)                                  [FAIL]
>   3 number written(4) != read(0)                                  [FAIL]
>   4 negnumber written(5) != read(0)                               [FAIL]
>   5 unsigned written(5) != read(0)                                [FAIL]
>   6 char written(1) != read(0)                                    [FAIL]
>   7 hex written(1) != read(0)                                     [FAIL]
>   8 pointer written(5) != 3                                       [FAIL]
>   Errors during this test: 8
> 
> The main issue was that glibc uses buffered writes by default.
> 
> I could fix them with fflush() (which we don't have so it required an
> ifndef), and this also made me realize that we were missing an fclose()
> as well for compatibility with glibc. With this it got better:
> 
>   Running test 'vfprintf'
>   0 empty "" = ""                                                  [OK]
>   1 simple "foo" = "foo"                                           [OK]
>   2 string "foo" = "foo"                                           [OK]
>   3 number "1234" = "1234"                                         [OK]
>   4 negnumber "-1234" = "-1234"                                    [OK]
>   5 unsigned "12345" = "12345"                                     [OK]
>   6 char "c" = "c"                                                 [OK]
>   7 hex "f" = "f"                                                  [OK]
>   8 pointer written(5) != 3                                       [FAIL]
>   Errors during this test: 1
> 
> This is caused by glibc emitting "(nil)" while we emit "0x0" for a NULL
> pointer since we use the same code as when dumping integers. I could fix
> that one as well by printing (void*)1 instead, which shows "0x1" for both.
> 
> This gives me the patch below on top of yours, which I think would make
> sense to integrate in this form or a simplified one if we manage to add
> fflush() and fclose() earlier.
> 
> What do you think ?
> 
> Thanks,
> Willy
> 
> 
> diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
> index 28a8d77078dc..2958dc3eca93 100644
> --- a/tools/testing/selftests/nolibc/nolibc-test.c
> +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> @@ -678,6 +678,7 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char
>  	int ret, fd, w, r;
>  	char buf[100];
>  	va_list args;
> +	FILE *memfile;
>  
>  	fd = memfd_create("vfprintf", 0);
>  	if (fd == -1) {
> @@ -685,8 +686,14 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char
>  		return 1;
>  	}
>  
> +	memfile = fdopen(fd, "w+");
> +	if (!memfile) {
> +		pad_spc(llen, 64, "[FAIL]\n");
> +		return 1;
> +	}
> +
>  	va_start(args, fmt);
> -	w = vfprintf(fdopen(fd, "w+"), fmt, args);
> +	w = vfprintf(memfile, fmt, args);
>  	va_end(args);
>  
>  	if (w != c) {
> @@ -695,12 +702,19 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char
>  		return 1;
>  	}
>  
> +#ifndef _NOLIBC_STDIO_H
> +	fflush(memfile);
> +#endif
>  	lseek(fd, 0, SEEK_SET);
>  
>  	r = read(fd, buf, sizeof(buf) - 1);
>  	buf[r] = '\0';
>  
> +#ifndef _NOLIBC_STDIO_H
> +	fclose(memfile);
> +#else
>  	close(fd);
> +#endif

Wouldn't it be nicer to implement fflush/fclose in nolibc?
I can send a v3 with that.

>  	if (r != w) {
>  		llen += printf(" written(%d) != read(%d)", w, r);
> @@ -737,7 +751,7 @@ static int run_vfprintf(int min, int max)
>  		CASE_TEST(unsigned);     EXPECT_VFPRINTF(5, "12345", "%u", 12345); break;
>  		CASE_TEST(char);         EXPECT_VFPRINTF(1, "c", "%c", 'c'); break;
>  		CASE_TEST(hex);          EXPECT_VFPRINTF(1, "f", "%x", 0xf); break;
> -		CASE_TEST(pointer);      EXPECT_VFPRINTF(3, "0x0", "%p", NULL); break;
> +		CASE_TEST(pointer);      EXPECT_VFPRINTF(3, "0x1", "%p", (void*)0x1); break;
>  		case __LINE__:
>  			return ret; /* must be last */
>  		/* note: do not set any defaults so as to permit holes above */
  

On Sun, Apr 02, 2023 at 05:17:53PM +0000, Thomas Weißschuh wrote:
> Wouldn't it be nicer to implement fflush/fclose in nolibc?

Yes that was my point, I just didn't know whether you still had some
time left to assign to this or not, hence my question.

> I can send a v3 with that.

Its currently running tests here. It looks pretty good, I guess I'm
going to bless it.

Thanks!
Willy